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NREL report finds hydrogen fuel cell bus fuel economy up to 1.4x that of diesel, 1.9x CNG

The US Department of Energy (DOE) Fuel Cell Technology Office (FCTO) has released the latest edition of an annual report showing that the average fuel economy of fuel cell electric buses from three fleets is 6.8 miles per diesel gallon equivalent (DGE) (ranging from 5.56 - 7.71 DGE), 1.4 times higher than conventional diesel buses (~4.2 miles per DGE) from one fleet and up to 1.9 times higher than compressed natural gas buses (~3.3 miles per DGE) in another fleet.

This demonstrates significant fuel economy improvement toward the DOE and Federal Transit Administration’s (FTA) target of 8 miles per DGE. FCEB durability has reached 23,000 hours, surpassing FCTO’s 2016 target of 18,000 hours, and range has reached up to 340 miles (547 km), more than 13% above the 2016 target of 300 miles (483 km).

However, NREL also noted that the fuel economy for the FCEBs has shown a decrease over time. This could be due to a variety of factors including changes in duty cycle, temperature, operator driving styles, fuel cell power plant degradation, and hydrogen station metering differences.

The report, entitled Fuel Cell Buses in US Transit Fleets: Current Status 2016 and published annually by the National Renewable Energy Laboratory (NREL), summarizes the progress of fuel cell electric bus (FCEB) development in the United States and discusses the achievements and challenges of introducing fuel cell propulsion in transit.

The 2016 report focuses on the August 2015–July 2016 time period for three demonstrations:

  • the Zero Emission Bay Area Demonstration Group;
  • the American Fuel Cell Bus Project at SunLine Transit Agency in California; and
  • the American Fuel Cell Bus Project at the University of California at Irvine (UCI)

The results for these buses account for more than 550,000 miles (885,139 km) traveled and 59,500 hours of fuel cell power system operation.

IMG_0355

NREL considers these FCEB designs to be around technology readiness level (TRL) 7—i.e., full-scale validation in a relevant environment. At this point in development, capital and operating costs for FCEBs are still much higher than those of conventional diesel technology. NREL noted that this is to be expected considering diesel is a very mature technology (TRL 9) and FCEBs are still in the development stage.

The fuel cell bus manufacturers continue to make significant progress toward meeting the durability target. In the 2015 report, NREL documented a single fuel cell power plant surpassing the 2016 target. At the end of the analysis period for this report (July 2016), that fuel cell power plant had reached 23,000 hours, nearing the ultimate target of 25,000 hours. A second fuel cell power plant has now surpassed the 2016 target, achieving 18,293 hours. Of the 18 fuel cell power plants included in the data set, 67% (12) have surpassed 13,000 hours of operation. The average hours accumulated is 12,302.

Despite the continued improvements in performance, fuel cell buses still face challenges to commercial viability, including:

  • Parts supply. Two of the agencies continue to experience some issues with availability of bus components that have a long lead time for delivery. This has improved over time as the project partners have learned what should be kept on hand. In some cases, bus components for the FCEB model are different from that of the diesel model so the bus parts inventory cannot be shared. The industry needs to further develop a robust supply chain or more shared components for these advanced components for FCEBs (as well as other electric drive buses).

  • Bus range/low fuel. AC Transit has reported that real-world bus range is lower than expected. Several factors contribute to the issue including operator familiarity and comfort level with the system, the fueling process, and differences in fueling rate between the two hydrogen stations. The flow rate of the station has an impact on the amount of hydrogen delivered to the tanks. The agency is addressing this challenge through continued training for operator and maintenance staff. It is difficult to measure real-world range because transit agencies typically fill the buses each day, regardless of the amount of fuel left in the tank. Over the last year, the average fill amount is 22.4 kg for the three evaluated fleets. This amount is less than 60% of the tank capacity. The buses are averaging 121 miles per day. This is more a function of how the buses are scheduled as opposed to the actual capability of the bus, NREL observed.

  • Maintenance staff. All transit agencies are experiencing issues with turnover of the most experienced staff through retirements or job changes. Fewer people are entering the field of technical repair, making new candidates scarce. This is particularly challenging for agencies with advanced technology buses, because technical schools are just now beginning to develop courses to handle maintenance and repair of these new technologies. Once these courses are available, there will be a lag time before graduates are ready to enter the market.

  • Maintenance costs. Maintenance costs for advanced-technology buses typically start low because the buses are under warranty and the manufacturer is covering the cost and taking an active, on-site role in troubleshooting and repair. Costs begin to increase as transit staff takes on more of the maintenance responsibilities and begins the learning curve to understand how to fully maintain the buses. As the staff becomes more proficient, the costs eventually stabilize. The transition of knowledge from the manufacturers to the transit staff is essential to commercializing the technology.

  • Purchase cost. The capital cost for FCEBs in 2010 was around $2.5 million. More recent orders for FCEBs have had an average cost of $1.8 million—a 28% decrease. Costs should continue to drop with increasing orders; the industry projects an order for 40 buses could result in costs closer to $1 million each.

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Comments

mahonj

What about a hybrid diesel bus (for instance using the GKN system).
This would be about the same as a hydrogen fuel cell with requiring H2 infrastructure and would presumably be way cheaper to purchase.

Change

And all the dummies will believe this is evidence that FCV are more economical (cents per mile cost) when in fact they are not. The result refers to energy efficiency not economics but the dummies will be fooled to think otherwise. By the way compare fuel efficiency of FCV to that of fuel efficiency of BEVs and you will find you need 4 times as much energy to go 1 mile in a FCV rather than a BEV. The math is simple but complex enough to fool the dummies. Making hydrogen using an electrolyser and compressing it for use in FCV results in a 50% loss. The FCV losses another 55% in the electric motor and fuel cell. There are almost none losses in a BEV. Charging a battery is 95% efficient and using the energy in the BEV is like 80% efficient. The EPA ratings provide more evidence of this. The best FCV are rated at 65 mpge and the best BEVs are rated at 136 mpge. So BEVs are more than twice as efficient for comparable vehicles. And remember to add the 50% loss for making H2 fuel and we get the number that FCV are 4 times as inefficient as BEVs. No R&D is going to change that.

Don’t be fooled by the FCV propaganda. It is an illusion about doing something good in order to shout up green critics when in fact the ones who propagate it has no intentions to do good. They just want to keep making unsustainable gassers while trying to look good in public with their fantasy FCV programs. I am so tired of it.

http://www.fueleconomy.gov/feg/PowerSearch.do?action=alts&path=3&year1=2016&year2=2017&vtype=Electric&srchtyp=newAfv

Davemart

In addition to their other advantages and ignoring faked up efficiency comparisons from ideologies, since they use oxygen and need it pure fuel cell buses actually clean the air, with one FC bus taking out the emissions of around 50 diesel cars according to Hyundai.

Or probably the particles from excessive tire wear of 'ludicrously' accelerating vehicles.

Jason Burr

One thing I do like is they are basically electric buses. I don't know how much extra cost it would incur, but running these as a hybrid between EV for where there are gantries to supply electricity and FCEV when the route takes the bus down a hiway (or other areas with no gantries) segment seems like a doable prospect.

Or another idea is to replace the diesel hybrid idea with a FC hybrid. Run the bus on batteries more and only run the FC plant at certain charge threshold. Additionally have fast charge facilities at major stops on routes to limit the FC usage.

Basically reduce the load on the FC plant by making it a range extender. Some cities like San Francisco have many electric buses, but also a mix with diesels and hybrids. By using a FC hybrid you gain flexibility instead of being stuck with certain buses on only some routes. I would suspect you could eliminate the diesels and some diesel hybrids if you change the FC to hybrid.

gryf

As this article points out "fuel cell buses still face challenges to commercial viability". Fuel Cell buses have been operating for over a decade and still cannot compete with either diesel or CNG buses.
However, this is not the case for Electric Buses. An Electric Bus 12 year life cycle costs are already cost competitive with diesel buses despite initially costing twice as much. Range and charging time are no longer an issue either. For example, the latest Proterra Catalyst E2 Electric bus has a 350 mile range and can be charged in less than 5 hours, a recent Forbes article discusses how Proterra biggest problem is meeting demand for their buses (http://www.forbes.com/sites/alanohnsman/2016/11/30/proterras-ryan-popple-is-on-a-mission-to-electrify-the-transit-bus-business/#5d72b1b61a49).

dursun

No mention of GHG

Peter_XX

If you also include "upstream" efficiency in the calculation, i.e. take fuel production into account, the diesel bus will be much better than the FC bus. So now you know why they did not do that.

SJC

If they can get 100 kW fuel cells for $10,000 they could start being used in more buses and trucks. Light rail could use them to get rid of the over head wires.

sd

gryf: The Forbes article and the Proterra website certainly make a strong case for just running Battery Electric buses as the long term cost is lower than either straight CNG or Diesel. I do know what the average transit bus runs in a day but I doubt that it is over 200 miles.

Henrik: I agree some of your points but the way you express them probably does not help your cause.

HarveyD

Combo FC + Batteries could be one of the best solution for many clean transport applications. Those, basically EV buses with FCs as range extenders, would have much better all weather extended range capabilities.

Clean storable H2 produced with excess REs will soon approach the cost of other clean 24/7 energies.

Near future 150 KW FCs will not cost much more and weight more than equivalent diesel ICEs and/or 150 kWh battery packs and will last 25,000+ hours.

One thing is almost certain; diesel trucks and buses will be progressively replaced with clean running Battery or FC units or most probably with combined Battery/FC units for extended range reasons.

B27Opel


Harvey D - a FC is already a "Combo FC+Battery" powertrain. Hence the "electric" in the article "Average fuel economy of fuel cell electric buses". However it is true that relative battery/FC stack sizing can still be a variable.

What seems to be missing from this article is to highlight that this is compared to a conventional Diesel and CNG bus. Those could be hybridized too, with likely 30%+ efficiency increases, bringing them in close comparison with this FC bus data.

The BEV FC comparison is much more complex, Henrik. You didn't mention recharge time, CO2 lifecycle concerns etc.

HarveyD

B27Opel. I agree with you and new near future super caps may do a better complementary job than batteries and would certainly recover more braking energy and last longer.

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